EP0674342A1 - Motif et procede d'evaluation d'un foyer - Google Patents

Motif et procede d'evaluation d'un foyer Download PDF

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Publication number
EP0674342A1
EP0674342A1 EP94929643A EP94929643A EP0674342A1 EP 0674342 A1 EP0674342 A1 EP 0674342A1 EP 94929643 A EP94929643 A EP 94929643A EP 94929643 A EP94929643 A EP 94929643A EP 0674342 A1 EP0674342 A1 EP 0674342A1
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EP
European Patent Office
Prior art keywords
pattern
transferred
focus
wafer
size
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP94929643A
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German (de)
English (en)
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EP0674342B1 (fr
EP0674342A4 (fr
Inventor
Akira Oki Electric Industry Co. Ltd. Watanabe
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Oki Electric Industry Co Ltd
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Oki Electric Industry Co Ltd
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Publication of EP0674342A4 publication Critical patent/EP0674342A4/fr
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Publication of EP0674342B1 publication Critical patent/EP0674342B1/fr
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    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03FPHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70Microphotolithographic exposure; Apparatus therefor
    • G03F7/70483Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
    • G03F7/7055Exposure light control in all parts of the microlithographic apparatus, e.g. pulse length control or light interruption
    • G03F7/70558Dose control, i.e. achievement of a desired dose
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/027Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03FPHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F1/00Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
    • G03F1/38Masks having auxiliary features, e.g. special coatings or marks for alignment or testing; Preparation thereof
    • G03F1/44Testing or measuring features, e.g. grid patterns, focus monitors, sawtooth scales or notched scales
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03FPHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70Microphotolithographic exposure; Apparatus therefor
    • G03F7/70483Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
    • G03F7/70605Workpiece metrology
    • G03F7/70616Monitoring the printed patterns
    • G03F7/70633Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03FPHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70Microphotolithographic exposure; Apparatus therefor
    • G03F7/70483Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
    • G03F7/70605Workpiece metrology
    • G03F7/70616Monitoring the printed patterns
    • G03F7/70641Focus

Definitions

  • This invention relates to a pattern for focus estimation and, more particularly, to a pattern for focus estimation to come in focus at an exposure process for a semiconductor device manufacturing process. Moreover, it relates to a method for estimating focus in use of the pattern for focus estimation.
  • Reduction projection exposure has conventionally been used for high resolution pattern formations, as described in "VLSI Technology Guide [Nyumon]" (Heibonshia), p. 143-144. With this method, any defect of a mask does not occur during the exposure process because the mask and the wafer do not contact with each other, so that a high yield can be ensured.
  • Apparatuses used for the reduction projection exposure method are referred to as steppers.
  • this reduction projection exposure method is described.
  • Light from a mercury lamp 171 as a light source passes through a filter and becomes light of a sole frequency. The light reaches a reticle 173, an original of a pattern, after passing through a condenser lens 172.
  • the light passed through transparent portions of the reticle comes into focus after passing through a reduction lens 174.
  • the light is automatically focalized according to respective exposure conditions by means of a sensor (not shown) provided near the light source for detecting the position of a wafer.
  • the wafer position set by the sensor and the focal position at which the optical system brings the light into focus are not always matched, and therefore, generally, the deviations are previously measured and required to be corrected.
  • a first invention is to provide a pattern (a pattern for focus estimation) used for a method (a method for estimating focus) for measuring deviations between a wafer position set by a sensor of a stepper apparatus and a focal position at which an optical system brings the light into focus.
  • a second invention is to provide a method for estimating focus in use of the pattern for focus estimation.
  • the pattern for focus estimation of the first invention is a pattern depicted on a body and has a pattern including, when light is illuminated out of a light source located over the body, a first pattern portion depicted with a resoluble line width onto a wafer located below the body, and a second pattern portion formed adjacently to the first pattern portion having very fine patterns either depicted with a non-resoluble line width or isolated with a non-resoluble space.
  • the method for estimating focus of the second invention is a process for transferring onto a wafer a pattern for focus estimation that has a pattern including, when light is illuminated out of a light source located over the body, a first pattern portion depicted with a resoluble line width onto a wafer located below the body, and a second pattern portion formed adjacently to the first pattern portion having very fine patterns either depicted with a non-resoluble line width or isolated with a non-resoluble space, and includes a process for transferring the pattern multiple times in varying distance between the pattern for focus estimation and a set position of the wafer, a process for measuring distance from an end of a first transferred portion corresponding to the first pattern portion to an end of a second transferred portion corresponding to the second pattern portion, of the respective transferred patterns that transferred onto the wafer by the multiple time transfer, and a process for judging the set position of the wafer coming in focus from the measured results.
  • Fig. 1 is a diagram illustrating a first reticle pattern for focus estimation of the invention.
  • line patterns 11 extending crosswise with width a ⁇ m are arranged with intervals of a ⁇ m lengthwise.
  • the pattern width a is a line width less than the resolution limitation of a stepper performing exposure.
  • N.A. Numerical Aperture of Lens
  • i-line 365 nm
  • the resolution limitation R of the stepper is, theoretically: ⁇ : Exposure Frequency
  • N.A.: Numerical Aperture of Lens k 0.5 (constant) therefore, Accordingly, the pattern width and pattern interval a can be equal to or less than 0.365 ⁇ m, theoretically.
  • Fig. 2(a) is a transferred pattern in the case that a value of the pattern width and pattern interval of the reticle pattern in Fig. 1 is 0.35 ⁇ m. Although the end of the line pattern is rounded, respective line patterns are separated.
  • Fig. 2(b) is a transferred pattern in the case that a value of the pattern width and pattern interval of the reticle pattern in Fig. 1 is 0.30 ⁇ m. The respective line patterns are not separated; the ends of the transferred patterns are corrugated.
  • Fig. 2(c) is a transferred pattern in the case that a value of the pattern width and pattern interval of the reticle pattern in Fig. 1 is 0.25 ⁇ m. The respective patterns are not separated; the transferred pattern is formed in a large square.
  • Fig. 2(d) is a transferred pattern in the case that a value of the pattern width and pattern interval of the reticle pattern in Fig. 1 is 0.20 ⁇ m. The respective patterns are not separated; the transferred pattern is formed in a large square.
  • the a value above is a numerical value when the pattern is transferred onto a wafer, and takes a value five times of it when the pattern is on the reticle (in the case of the 1/5 reduction).
  • the exposure period was 160 msec.
  • the patterns are not precisely separated or do not make distinctive resolution when the patterns have the pattern width and pattern interval equal to or less than the resolution limitation; when the pattern width and pattern interval are equal to or less than 0.25 ⁇ m, the pattern is formed in a large square in appearance.
  • the reticle pattern in Fig. 1 is prepared.
  • the reticle pattern whose pattern width and pattern interval are 0.25 ⁇ m (Fig. 2(c)) is employed.
  • Fig. 2(c) when this reticle pattern is employed, the form of the transferred pattern becomes a large square in appearance, so that the size is easily measured.
  • This reticle pattern is transferred (exposed and developed) onto a wafer in varying the wafer position to be brought to plural subdivided areas of the wafer on which photoresist has previously coated.
  • the exposure amount was a constant; the exposure time was set at 160 msec.
  • the wafer position set up by the sensor is made as the reference (0), and the wafer position is varied from the reference by 0.1, 0.2, and 0.3 ⁇ m upward (+) and by 0.1, 0.2, and 0.3 ⁇ m downward (-).
  • the size in the X axial direction of the transferred patterns transferred onto the wafer is measured by an optical size measuring equipment.
  • Graph 1 in Fig. 3 shows a relation between size in the X axial direction and wafer position in this case.
  • the maximum value of Graph 1 becomes the wafer position (the best focus position) at which the pattern comes into focus. That is, in this case, the position at which the pattern comes into focus has shifted 0.1 ⁇ m from the set position by the sensor.
  • the best focus position can be judged from the correlation diagram of the wafer position and the size of the transferred pattern in the X axial direction, and therefore, the pattern can be formed more accurately by correcting the set position by the sensor in consideration of the deviations between the best focus position and the set position by the sensor.
  • Graph 2 is, here, data for describing the effects of the invention and is a measurement result of size of the transferred pattern in the X axial direction when it is transferred using a reticle pattern with its pattern width and pattern interval of 0.5 ⁇ m.
  • the pattern width and pattern interval are 0.5 ⁇ m
  • the respective line patterns are separated and made distinctively, and the whole shape does not constitute a square. That was measured by an SEM type size measuring equipment.
  • the reason that the SEM type size measuring equipment was used is that very fine line width as of 0.5 ⁇ m cannot be measured by an optical size measuring equipment. Its details are specifically described in a third embodiment.
  • the wafer position at which the pattern comes into focus (the best focus position) is at +0.1 ⁇ m
  • the deviation (conversion differential) between the size in the X axial direction where the wafer position is at -0.3 ⁇ m and the size in the X axial direction at a point of inflection (where the wafer position is at +0.1 ⁇ m) is about 0.34 ⁇ m.
  • the conversion differential is about 0.1 ⁇ m.
  • the method for estimating focus of the invention has sensitivity three times or more.
  • the conversion amount of the size of the transferred pattern against the changes of the wafer position can be made larger, so that the best focus position can be judged easily. Consequently, from the judgment of the best focus position, the pattern can be accurately formed by finely adjusting the wafer position.
  • the maximum value indicates the wafer position (the best focus position) at which the pattern comes into focus; where they are few, the minimum value indicates so.
  • Fig. 5 shows a second reticle pattern 50 for focus estimation of the invention, and plural triangular serrate portions 52 are formed around a square pattern 51.
  • the shape of the square pattern 51 is changeable when the change is proper.
  • the triangular serrate portion 52 is a right angled isosceles triangle having base 2 a ⁇ m and height a ⁇ m.
  • Figs. 6(a), 6(b), 6(c) and 6(d) transferred patterns when the reticle pattern for focus estimation in Fig. 5 is transferred onto a wafer, are shown.
  • Fig. 6(a) is a transferred pattern where the a value in Fig. 5 is 0.35 ⁇ m. The end of the transferred pattern is serrate.
  • Fig. 6(b) is a transferred pattern where the a value in Fig. 5 is 0.30 ⁇ m. The transferred pattern is almost square.
  • Fig. 6(c) is a transferred pattern where the a value in Fig. 5 is 0.25 ⁇ m. The transferred pattern is almost square.
  • Fig. 6(d) is a transferred pattern where the a value in Fig. 5 is 0.20 ⁇ m.
  • the transferred pattern is almost square.
  • the a value is a numerical value when the pattern is transferred onto a wafer, and takes a value five times of it on the reticle (in the case of the 1/5 reduction).
  • the exposure period was set to 160 msec.
  • the pattern is not made accurately as distinctive; with the pattern width and pattern interval a of 0.30 ⁇ m or below, the pattern is formed in a square approximately in appearance.
  • the conversion amount of the size of the transferred pattern against the changes of the wafer position can be larger, the best focus position can be easily judged. Accordingly, from the judgment of the best focus position, the pattern can be accurately formed by finely adjusting the wafer position.
  • Fig. 7(a) is a third reticle pattern for focus estimation of the invention, and plural rectangular comb tooth portions 72 are formed around a first square pattern portion 71 of 25 ⁇ m square.
  • the shape of the first square pattern portion 71 is changeable when the change is proper, and can be 10 or 40 ⁇ m square. It can be rectangular.
  • Fig. 7(b) is an enlarged view of the upper left part (part A) of Fig. 7(a).
  • the rectangular comb tooth portion 72 is constituted of a rectangular with its width a1 and length a2 arranged at every width 3a.
  • a method for estimating focus in use of the reticle pattern shown in Figs. 7(a), 7(b) is described as follows.
  • Table 1 shows data of the conversion differentials of (i) to (vi) above.
  • the conversion amount of the pattern size against the changes of the wafer position can be made larger. Accordingly, the best focus position is judged easily, and patterns can be formed accurately by finely adjusting the wafer position from the judgment of the best focus position.
  • Figs. 14, 15 show other examples.
  • Fig. 14 is an example in which the shape of the serrate portions is formed as an isosceles triangle;
  • Fig. 15 is an example in which the shape of the comb tooth portion is made as a square.
  • the best focus position can be easily judged because, at the process for transferring the pattern for focus estimation of the first invention onto the wafer, the pattern is transferred multiple times in varying distance between the pattern for focus estimation and the set position of the wafer; the distance from the end of the first transferred portion corresponding to the first pattern portion to the end of the second transferred portion corresponding to the second pattern portion, of the respective transferred patterns which are transferred onto the wafer by the multiple time transfers, is measured; the set position of the wafer at which the pattern comes into focus is judged from the measurement results.
  • the patterns can be accurately formed by finely adjusting the wafer position.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Manufacturing & Machinery (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
  • Preparing Plates And Mask In Photomechanical Process (AREA)
EP94929643A 1993-10-13 1994-10-12 Procede d'evaluation du foyer Expired - Lifetime EP0674342B1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP256003/93 1993-10-13
JP25600393 1993-10-13
JP25600393 1993-10-13
PCT/JP1994/001705 WO1995010849A1 (fr) 1993-10-13 1994-10-12 Motif et procede d'evaluation d'un foyer

Publications (3)

Publication Number Publication Date
EP0674342A1 true EP0674342A1 (fr) 1995-09-27
EP0674342A4 EP0674342A4 (fr) 1996-02-21
EP0674342B1 EP0674342B1 (fr) 2001-09-05

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EP94929643A Expired - Lifetime EP0674342B1 (fr) 1993-10-13 1994-10-12 Procede d'evaluation du foyer

Country Status (5)

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EP (1) EP0674342B1 (fr)
JP (1) JP3299758B2 (fr)
KR (1) KR100313191B1 (fr)
DE (1) DE69428185T2 (fr)
WO (1) WO1995010849A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1081483A3 (fr) * 1999-09-03 2001-08-16 Oki Electric Industry Company, Limited Motif de mesure de l'aberration d'une lentille d'un photorépéteur et méthode d'évaluation des caractéristiques de l'aberration d'une lentille d'un photorépéteur

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3550394B2 (ja) 2002-07-16 2004-08-04 沖電気工業株式会社 焦点ずれ測定方法及び焦点位置合わせ方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0111635A2 (fr) * 1982-12-20 1984-06-27 International Business Machines Corporation Méthode de sélection pour l'ajustment optimal de la focalisation d'un instrument optique
EP0338200A2 (fr) * 1988-03-31 1989-10-25 International Business Machines Corporation Méthode et appareil pour caractériser des systèmes optiques

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4979472A (fr) * 1972-12-06 1974-07-31
JPS5877231A (ja) * 1981-11-04 1983-05-10 Hitachi Ltd レジストパタ−ンのテ−パ形成方法
JPS6319830A (ja) * 1986-07-14 1988-01-27 Oki Electric Ind Co Ltd 解像度チエツク用パタ−ン

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0111635A2 (fr) * 1982-12-20 1984-06-27 International Business Machines Corporation Méthode de sélection pour l'ajustment optimal de la focalisation d'un instrument optique
EP0338200A2 (fr) * 1988-03-31 1989-10-25 International Business Machines Corporation Méthode et appareil pour caractériser des systèmes optiques

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
MOTOROLA TECHNICAL DEVELOPMENTS, vol. 16, August 1992 SCHAUMBURG, ILLINOIS US, pages 121-124, XP 000310385 S. MALHOTRA ET AL. 'METHOD FOR DETERMINING STEPPER FOCUS AND OFFSETS' *
See also references of WO9510849A1 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1081483A3 (fr) * 1999-09-03 2001-08-16 Oki Electric Industry Company, Limited Motif de mesure de l'aberration d'une lentille d'un photorépéteur et méthode d'évaluation des caractéristiques de l'aberration d'une lentille d'un photorépéteur
US6654107B1 (en) 1999-09-03 2003-11-25 Oki Electric Industry Co., Ltd. Stepper lens aberration measurement pattern and stepper lens aberration characteristics evaluating method

Also Published As

Publication number Publication date
DE69428185T2 (de) 2002-07-04
KR950704805A (ko) 1995-11-20
JP3299758B2 (ja) 2002-07-08
KR100313191B1 (ko) 2002-04-06
EP0674342B1 (fr) 2001-09-05
EP0674342A4 (fr) 1996-02-21
DE69428185D1 (de) 2001-10-11
WO1995010849A1 (fr) 1995-04-20

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